Pressure-induced changes of the vibrational modes of spin-crossover complexes studied by nuclear resonance scattering of synchrotron radiation

TL;DR

This study investigates how pressure affects vibrational modes in spin-crossover complexes using nuclear resonance scattering, revealing that pressure induces a spin transition characterized by hardening of iron-bond stretching modes.

Contribution

It provides the first detailed analysis of pressure-induced vibrational changes in spin-crossover complexes using nuclear resonance scattering.

Findings

Pressure induces spin transition from HS to LS state.

LS state shows hardened iron-bond stretching modes.

Spin transition occurs at pressures up to 2.6 GPa.

Abstract

Nuclear inelastic scattering (NIS) spectra were recorded for the spin-crossover complexes STP and ETP (STP = [Fe(1,1,1-trisf[N-(2-pyridylmethyl)-N-methylamino]methylg- ethane)](ClO4)2 and ETP = [Fe(1,1,1-trisf[N-(2-pyridylmethyl)-N-methylamino]methylg-butane)](ClO4)2) at 30 K and at room temperature and also at ambient pressure and applied pressure (up to 2.6 GPa). Spin transition from the high-spin (HS) to the low-spin (LS) state was observed by lowering temperature and also by applying pressure at room temperature and has been assigned to the hardening of iron-bond stretching modes due to the smaller volume in the LS isomer.